The purpose of this book is not strictly historical but theological and pastoral. The main emphasis is that God is at work and plans to live again with His people in Jerusalem. He will save them from their enemies and cleanse them from sin.
Zechariah's concern for purity is apparent in the temple, priesthood and all areas of life as the prophecy gradually eliminates the influence of the governor in favor of the high priest, and the sanctuary becomes ever more clearly the centre of messianic fulfillment. The prominence of prophecy is quite apparent in Zechariah, but it is also true that Zechariah (along with Haggai) allows prophecy to yield to the priesthood; this is particularly apparent in comparing Zechariah to "Third Isaiah" (chapters 55–66 of the Book of Isaiah whose author was active sometime after the first return from exile.
This blog was originally written by Pastor Doug Bartel of Hillcrest Church, starting in Spring 2009. Keep that in mind if you read anything that doesn't quite add up to the time of year.